Sheet folding apparatus

ABSTRACT

Buckles (b 1  to b 4 ) are each provided with a stopper (S 1  to S 4 ). A pair of uptake rollers (W, W 1 ); (W, W 2 ); (W 2,  W 3 ); (W 3,  W 4 ), to supply paper to the buckles, and a pair of discharge rollers (W, W 2 ); (W 2,  W 3 ); (W 3;  W 4 ); (W 4,  W 5 ), to fold the portion of the paper discharged outside the buckles, are disposed at each buckle inlet. The discharge roller for a previous buckle simultaneously functions as the uptake roller for the next buckle, and the paper is sequentially introduced into the buckles and folded into a bellows form. Stopper drive mechanisms (d 1  to d 4 ) are integrally controlled by a control unit (C). The control unit receives input for the value of the difference in length between the last folded piece and the remaining folded piece of a bellows-folded paper in which a folding error has occurred, divides the length difference by the number of buckles, and sends control instructions to slide the stoppers in the same direction as the buckle inlet (e) relative to the stopper drive mechanisms for the length obtained by division in order to make the length difference zero.

TECHNICAL FIELD

The present invention relates to a sheet folding apparatus,particularly, a sheet folding apparatus which folds up a sheet like anaccordion by alternating mountain and valley folds of the sheet in adirection perpendicular to a sheet feed direction.

BACKGROUND ART

In the prior art, there are some sheet folding apparatuses in which aplurality of folding roller pairs is arranged and a sheet is folded uplike an accordion by the sheet being nipped between the folding rollerpairs sequentially (See also, for example, Patent Documents 1 and 2).

FIG. 7 is a schematic view illustrating an configuration of suchconventional sheet folding apparatus. In FIG. 7, an alphabet Adesignates a sheet supply unit, an alphabet B designates a sheetconveyance unit and an alphabet C designates a sheet folding unit. Thesheet supply unit has a sheet supply table 1 arranged for verticalmotion and supporting a sheet bundle thereon, and a roller 2 feeding theuppermost sheet P of the sheet bundle to the sheet conveyance unit B oneby one. The sheet conveyance unit B has a conveyor belt 3 conveying thesheet P supplied from the sheet supply unit A to the sheet folding unitC, and a group of idle rollers 4 preventing the sheet P from liftingfrom the conveyor belt 3.

The sheet folding unit C has a plurality of buckles b1-b4, and each ofthe buckles b1-b4 is provided with a stopper S1-S4 whose positon isadjustable. Near an inlet of each of the buckles b1-b4, a pair of drivenintake rollers W, W1; W, W2; W2, W3; W3, W4 is arranged opposite to eachother so as to take the sheet P into the associated buckle b1-b4 and apair of driven discharge rollers W, W2; W2, W3; W3, W4; W4, W5 isarranged opposite to each other so as to fold a portion of the sheet Pexteriorly protruding from the associated buckle b1-b4.

Then a discharge roller associated with a previous buckle concurrentlyserves as an intake roller associated with the next buckle and thereby,the sheet P is sequentially taken into a plurality of buckles and foldedlike an accordion by alternating mountain and valley folds of the sheetin a direction perpendicular to a sheet feed direction depending on thenumber of the buckles.

In particular, when the folding operation is carried out, each of thestopper S1-S4 is fixed to a positon corresponding to a folding positonof the sheet P. Then the sheet P fed from the sheet conveyance unit B isnipped between the pair of rollers W and W1 so as to be inserted intothe buckle b1. When the leading end of the sheet P collides with thestopper S1 of the buckle b1, the sheet P is deflected from the buckle b1in the neighborhood of the inlet of the buckle b1, the deflected portionis nipped between the pair of rollers W2 and W, and the sheet P isfolded to one side.

Next, the folded sheet P is inserted into the buckle b2 with its foldline in the lead. When the leading end of the folded sheet P collideswith the stopper S2 of the buckle b2, the folded sheet P is deflectedfrom the buckle b2 in the neighborhood of the inlet of the buckle b2,the deflected portion is nipped between the pair of rollers W2 and W3,and the folded sheet is further folded to the other side. Thus the sheetP is folded at two positions. Similarly, the twice folded sheet P isfurther folded by the buckle b3 together with the pair of rollers W2 andW3 and the pair of rollers W3 and W5, and further folded by the buckleb4 together with the rollers W3, W4 and W5.

Consequently, the sheet folded up like an accordion by alternatingmountain and valley folds of the sheet in a direction perpendicular to asheet feed direction is discharged from the apparatus.

According to this apparatus, the length of each flap of the accordionfold can be changed by adjusting the position of the stoppers S1-S4 ofthe buckles b1-b4. In order to obtain an evenly accordion-folded sheet(an accordion fold whose flaps have the same length), all of thestoppers S1-S4 are set in such a way that they are arranged at the samedistance from the inlets of the associated buckles b1-b4.

However, a collision speed of a sheet P slightly differs from onestopper to another, and the firmness and deflection characteristics arediffer from one sheet to another. Therefore, in the conventional sheetfolding apparatus, there arises a folding error that causes anaccordion-folded sheet whose last flap is longer or shorter than theremaining flaps.

In such case, conventionally, a difference in length between the lastflap and the remaining flaps is measured, and, based on the measuredvalue, the positions of the stoppers S1-S4 of the buckles b1-b4 arereset individually in consideration of a difference between the setvalue and a flap length when a sheet is actually folded. However, thework of resetting needs skill and a long time.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: JP 2001-88227 A

Patent Document 2: JP 3253669 B

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

It is, therefore, an object of the present invention to provide a sheetfolding apparatus capable of easily resetting positions of stoppers in ashort time when the folding error occurs in a process of evenly foldingup a sheet like an accordion.

Means for Solving the Problems

In order to achieve the object, according to the present invention,there is provided a sheet folding apparatus which folds up a sheet likean accordion by alternating mountain and valley folds of the sheet in adirection perpendicular to a sheet feed direction, the sheet foldingapparatus comprising: a sheet supply unit sequentially feeding the sheetfrom a sheet stack; and a sheet folding unit folding the sheet fed fromthe sheet supply unit in the direction perpendicular to the sheet feeddirection, the sheet supply unit comprising: a shelf on which the sheetstack is placed; a conveyor belt extending between the shelf and thesheet folding unit; and a sheet feeder feeding the sheet from the sheetstack to the conveyor belt one by one, the sheet folding unitcomprising: a plurality of buckles into which the sheet fed from theconveyor belt is inserted sequentially; and a stopper attached to eachof the buckles so as to be slidable along the sheet feed direction,wherein, each time the sheet is inserted into the buckles, the sheet ispositioned at a preset folding position by colliding with the associatedstopper at the leading end thereof, the sheet folding unit furthercomprising: a stopper drive mechanism arranged at each of the buckles soas to move the associated stopper; a pair of driven intake rollersarranged in the neighborhood of an inlet of each of the buckles andopposed to each other so as to take the sheet in the associated buckle;and a pair of driven discharge rollers arranged in the neighborhood ofthe inlet of each of the buckles and opposed to each other so as to folda portion of the sheet exteriorly protruding from the associated buckle,the discharge roller associated with a previous buckle concurrentlyserving as the intake roller associated with the next buckle, therebythe sheet being sequentially inserted into the buckles so as to befolded at the number of times corresponding to the number of thebuckles, characterized in that the sheet folding apparatus furthercomprises a control unit integrally controlling the stopper drivemechanisms of the sheet folding unit, and the control unit receives aninput of a difference in length between the last flap and the remainingflaps of an accordion-folded sheet accompanied with a folding error anddivides the difference in length by the number of the buckles, whereinwhen the last flap is longer than the remaining flaps, in order toeliminate the difference in length, the control unit sends controlsignals to each of the stopper drive mechanisms in such a way that theassociated stopper is moved in a direction away from the inlet of theassociated buckle by the distance corresponding to the result of thedivision, and when the last flap is shorter than the remaining flaps, inorder to eliminate the difference in length, the control unit sendscontrol signals to each of the stopper drive mechanisms in such a waythat the associated stopper is moved in a direction toward the inlet ofthe associated buckle by the distance corresponding to the result of thedivision.

Effect of the Invention

According to the present invention, the sheet folding apparatuscomprises the control unit integrally controlling the stoppers of thebuckles of the sheet folding unit, and when the folding error occurs ina process of evenly folding up a sheet like an accordion, the positionsof the stoppers of the buckles are automatically reset so as to correctthe folding error just by inputting to the control unit a value of adifference in length between the last flap and the remaining flaps ofthe accordion-folded sheet accompanied with the folding error, andthereby, it is possible to easily reset the positions of the stoppers ina short time when the folding error occurs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a configuration of a sheet foldingapparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing a configuration of a sheet foldingunit of the sheet folding apparatus shown in FIG. 1.

FIGS. 3A through 3C are perspective views showing examples of accordionfold achieved by the sheet folding apparatus shown in FIG. 1.

FIG. 4 is a view showing a screen displayed on a touch screen of thesheet folding apparatus shown in FIG. 1.

FIG. 5 is a view showing a screen displayed on the touch screen of thesheet folding apparatus shown in FIG. 1.

FIG. 6 is a view showing a screen displayed on the touch screen of thesheet folding apparatus shown in FIG. 1.

FIG. 7 is a schematic view showing a configuration of a conventionalsheet folding apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment according to the present invention will beexplained below with reference to the accompanying drawings. FIG. 1 is aschematic view showing a configuration of a sheet folding apparatusaccording to an embodiment of the present invention, and FIG. 2 is anenlarged view showing a configuration of a sheet folding unit of thesheet folding apparatus shown in FIG. 1.

Referring to FIG. 1, the sheet folding apparatus of the presentinvention comprises a sheet supply unit A sequentially feeding the sheetP from a sheet stack M and a sheet folding unit B folding the sheet Pfed from the sheet supply unit A in the direction perpendicular to thesheet feed direction.

The sheet supply unit A comprises a vertically movable shelf 1 on whichthe sheet stack M is placed, a conveyor belt 2 extending between theshelf 1 and the sheet folding unit B and a sheet feeder 3 feeding theuppermost sheet P of the sheet stack M to the conveyor belt 2 one byone. In this embodiment, the sheet feeder 3 consists of a driven rollerarranged above the front end of the shelf 1. In FIG. 1, the referencenumeral 4 designates a group of idle rollers preventing the sheet P fromlifting from the conveyor belt 3.

The sheet folding unit B comprises a plurality of buckles (in thisembodiment, four buckles b1-b4) into which the sheet P fed from theconveyor belt 2 is inserted sequentially, and a stopper S1-S4 attachedto each of the buckles b1-b4 so as to be slidable along the sheet feeddirection. In this case, each of the buckles b1-b4 is provided with aguide rail (not shown) extending parallel to the associated buckle, andthe stoppers S1-S4 are attached to the guide rails for slide movement.Each time the sheet P is inserted into the buckles b1-b4, the sheet S ispositioned at a preset folding position by colliding with the associatedstopper S1-S4 at the leading end thereof.

The sheet folding unit B further comprises a stopper drive mechanismd1-d4 arranged at each of the buckles b1-b4 so as to move the associatedstopper S1-S4.

Referring to FIG. 2, in this embodiment, each of the stopper drivemechanisms d1-d4 consists of a threaded shaft 5 of a ball screw, a motor6 attached to the buckle b1-b4 so as to rotate the thread shaft 5, and anut (not shown) of the ball screw arranged at the stopper S1-S4 andengaging with the threaded shaft 5. The stopper S1-S4 is engaged withthe threaded shaft 5 through the nut.

Thus the stopper S1-S4 is moved in directions toward and away from aninlet e of the associated buckle b1-b4 by clockwise and counterclockwiserotations of the motor 6.

A configuration of the stopper drive mechanism d1-d4 is not limited tothis embodiment. Instead of a combination of a ball screw and a motor,for example, a combination of an endless belt extending between a pairof pulleys in a direction parallel to the buckle b1-b4 and a motorrotating one of the pulleys may be used. In this case, the stopper S1-S4is fixed to the endless belt.

The stopper drive mechanisms d1-d4 are integrally controlled by acontrol unit C.

A pair of driven intake rollers W, W1; W, W2; W2, W3; W3, W4 is arrangedin the neighborhood of the inlet e of each of the buckles b1-b4 andopposed to each other so as to take the sheet in the associated buckleb1-b4. A pair of driven discharge rollers W, W2; W2, W3; W3, W4; W4, W5is also arranged in the neighborhood of the inlet e of each of thebuckles b1-b4 and opposed to each other so as to fold a portion of thesheet P exteriorly protruding from the associated buckle b1-b4.

The discharge roller associated with a previous buckle concurrentlyserving as the intake roller associated with the next buckle, therebythe sheet P being sequentially inserted into the buckles so thatmountain and valley folds of the sheet P are alternated in a directionperpendicular to the sheet feed direction at the number of timescorresponding to the number of the buckles and an accordion-folded sheetis obtained.

Namely, the sheet P fed from the conveyor belt 2 of the sheet supplyunit A is nipped between the pair of rollers W and W1 so as to beinserted into the buckle b1. When the leading end of the sheet Pcollides with the stopper S1 of the buckle b1, the sheet P is deflectedfrom the buckle b1 in the neighborhood of the inlet of the buckle b1,the deflected portion is nipped between the pair of rollers W2 and W,and the sheet P is folded to one side (first fold).

Next, the folded sheet P is inserted into the buckle b2 with its foldline in the lead. When the leading end of the folded sheet P collideswith the stopper S2 of the buckle b2, the folded sheet P is deflectedfrom the buckle b2 in the neighborhood of the inlet of the buckle b2,the deflected portion is nipped between the pair of rollers W2 and W3,and the folded sheet is further folded to the other side (second fold).

Similarly, the twice folded sheet P is further folded by the buckle b3together with the pair of rollers W2 and W3 and the pair of rollers W3and W5 (third fold), and further folded by the buckle b4 together withthe rollers W3, W4 and W5 (fourth fold). Then the accordion-folded sheetP is discharged from the sheet folding apparatus.

In the sheet folding apparatus according to the present invention, asshown in FIG. 3A, in order to obtain an evenly accordion-folded sheet P(an accordion fold whose flaps P1-P5 have the same length), positions ofthe stoppers S1-S4 of the buckles b1-b4 are preset by the control unit C(regularly, all of the stoppers S1-S4 are set in such a way that theyare arranged at the same distance from the inlets of the associatedbuckles b1-b4).

However, a collision speed of a sheet P slightly differs from onestopper to another, and the firmness and deflection characteristics arediffer from one sheet to another. Consequently, as shown in FIG. 3B,there arises a folding error that causes an accordion-folded sheet Pwhose last flap P5 is longer than the remaining flaps P1-P4 (L1), or anaccordion-folded sheet P whose last flap P5 is shorter than theremaining flaps P1-P4 (L2).

According to the present invention, when such folding error occurs, atfirst, an operator measures a difference in length between the last flapP5 and the remaining flaps P1-P4 of an accordion-folded sheet Paccompanied with a folding error.

Then the control unit C receives an input of the measured value of thedifference of length, and divides the difference in length by the numberof the buckles b1-b4 (in this embodiment, four). When the last flap P5is longer than the remaining flaps P1-P4 (FIG. 3B), in order toeliminate the difference in length, the control unit C sends controlsignals to each of the stopper drive mechanisms d1-d4 in such a way thatthe associated stopper S1-S4 is moved in a direction away from the inlete of the associated buckle b1-b4 by the distance corresponding to theresult of the division (L1/4), and when the last flap P5 is shorter thanthe remaining flaps P1-P4, in order to eliminate the difference inlength, the control unit C sends control signals to each of the stopperdrive mechanisms d1-d4 in such a way that the associated stopper S1-S4is moved in a direction toward the inlet e of the associated buckleb1-b4 by the distance corresponding to the result of the division.

In this case, when the input value of the difference in length cannot bedivided evenly by the number of the buckles, the control unit C controlsthe stopper drive mechanisms d1-d4 based on a value obtained by roundingor rounding up or rounding down the result of the division.

In this embodiment, the control unit C comprises a touch screen (notshown) as an input means. A screen displayed on the touch screen forreceiving an input of setting values of positions of the stoppers S1-54is shown in FIG. 4.

In FIG. 4, the reference numeral 7 a designates an entry field for thesetting value of a position of the stopper S1 of the first buckle b1,and the reference numeral 7 b designates an entry field for settingvalue of a position of the stopper S2 of the second buckle b2, and thereference numeral 7 c designates an entry field for the setting value ofa position of the stopper S3 of the third buckle b3, and the referencenumeral 7 d designates an entry field for setting value of a position ofthe stopper S4 of the fourth buckle b4. As the position of each of thestopper S1-S4, a distance from the inlet of the associated buckle to thestopper S1-S4 is inputted.

In FIG. 4, the same setting value (165.0 mm) is inputted in each ofentry fields 7 a-7 d. The numeral values are inputted through a numerickeypad (not shown) as well as a pair of “+” and “−” buttons which isarranged at the right side of each of the entry fields 7 a-7 d.

After the input of the setting values, the sheet folding apparatusstarts operating. Then when the folding error occurs, a difference inlength between the last flap and the remaining flaps of theaccordion-folded sheet accompanied with the folding error is measured byan operator.

Next, the display on the touch screen is switched to a display for inputof the measured value as shown in FIG. 5. In FIG. 5, the referencenumeral 8 designates an entry field for the measured value. When thelast flap is longer than the remaining flaps of the accordion-foldedsheets, the measured value (the difference in length) as positivenumeric value is inputted to the entry field 8, and when the last flapis shorter than the remaining flaps, the measured value (the differencein length) as negative numeric value is inputted to the entry field 8.

In FIG. 5, the last flap is 8 mm longer than the remaining flaps andtherefore, positive numeric value of “+8 mm” is inputted to the entryfield 8.

Thus the measured value of “+8 mm” is inputted to the control unit C bythe operator through the touch screen.

After the input of the measured value, the display on the touch screenis switched to the display for input of the setting values of positionsof the stoppers again. Now the result of the division by the controlunit C is 8 mm/4=2 mm and therefore, in order to move all of thestoppers S1-S4 by 2 mm in a direction away from the inlets e of thebuckles b1-b4, the control unit C changes all of the setting values“165.0 mm” which have been inputted to the entry fields 7 a-7 d on thedisplay to “167.0 mm”. At the same time, the control unit C sendscontrol signals to all of the stopper drive mechanisms so as to move thestoppers based on the changed setting values, thereby the folding erroris corrected.

According to the present invention, when the folding error occurs in aprocess of evenly folding up a sheet like an accordion, the positions ofthe stoppers of the buckles are automatically reset so as to correct thefolding error just by inputting to the control unit a value of adifference in length between the last flap and the remaining flaps ofthe accordion-folded sheet accompanied with the folding error, andthereby, it is possible to easily reset the positions of the stoppers ina short time when the folding error occurs.

DESCRIPTION OF REFERENCE NUMERALS

-   1 Shelf-   2 Conveyor belt-   3 Sheet feeder-   4 Group of idle rollers-   5 Threaded shaft-   6 Motor-   7 a-7 d Entry field for setting value of a position of stopper of    buckle-   A Sheet supply unit-   B Sheet folding unit-   C Control unit-   M Sheet stack-   S1-S4 Stopper-   P Sheet-   P1-P5 Flap-   W, W1; W, W2; W2, W3; W3, W4 Intake roller-   W, W2; W2, W3; W3, W4; W4, W5 Discharge roller-   b1-b4 Buckle-   d1-d4 Stopper drive mechanism-   e Inlet of buckle

1. A sheet folding apparatus which folds up a sheet like an accordion byalternating mountain and valley folds of the sheet in a directionperpendicular to a sheet feed direction, the sheet folding apparatuscomprising: a sheet supply unit sequentially feeding the sheet from asheet stack; and a sheet folding unit folding the sheet fed from thesheet supply unit in the direction perpendicular to the sheet feeddirection, the sheet supply unit comprising: a shelf on which the sheetstack is placed; a conveyor belt extending between the shelf and thesheet folding unit; and a sheet feeder feeding the sheet from the sheetstack to the conveyor belt one by one, the sheet folding unitcomprising: a plurality of buckles into which the sheet fed from theconveyor belt is inserted sequentially; and a stopper attached to eachof the buckles so as to be slidable along the sheet feed direction,wherein, each time the sheet is inserted into the buckles, the sheet ispositioned at a preset folding position by colliding with the associatedstopper at the leading end thereof, the sheet folding unit furthercomprising: a stopper drive mechanism arranged at each of the buckles soas to move the associated stopper; a pair of driven intake rollersarranged in the neighborhood of an inlet of each of the buckles andopposed to each other so as to take the sheet in the associated buckle;and a pair of driven discharge rollers arranged in the neighborhood ofthe inlet of each of the buckles and opposed to each other so as to folda portion of the sheet exteriorly protruding from the associated buckle,the discharge roller associated with a previous buckle concurrentlyserving as the intake roller associated with the next buckle, therebythe sheet being sequentially inserted into the buckles so as to befolded at the number of times corresponding to the number of thebuckles, characterized in that the sheet folding apparatus furthercomprises a control unit integrally controlling the stopper drivemechanisms of the sheet folding unit, and the control unit receives aninput of a difference in length between the last flap and the remainingflaps of an accordion-folded sheet accompanied with a folding error anddivides the difference in length by the number of the buckles, whereinwhen the last flap is longer than the remaining flaps, in order toeliminate the difference in length, the control unit sends controlsignals to each of the stopper drive mechanisms in such a way that theassociated stopper is moved in a direction away from the inlet of theassociated buckle by the distance corresponding to the result of thedivision, and when the last flap is shorter than the remaining flaps, inorder to eliminate the difference in length, the control unit sendscontrol signals to each of the stopper drive mechanisms in such a waythat the associated stopper is moved in a direction toward the inlet ofthe associated buckle by the distance corresponding to the result of thedivision.